Boundary marker for Camberwell Parish on the route of the Effra at Gipsy Hill, where the fact of the watercourse there being a river was re-discovered in the 1920s.

The River Effra is a river in south London, England, mainly underground — due to its history and the introduction of a separate surface water drainage system its contours have been used for a sewer similar to the Walbrook.

The main course of the River Effra was converted into a sewer and culverts accessible through the sewers on Effra Road in Brixton,[4] South London and through a drainage grate in the crypts under St. Luke's Church, West Norwood, South London.

Directionally the Effra travelled NNW, briefly NNE, NNW then a short stretch from Kennington WNW.[3]

One branch of the Effra rises near Harold Road in Upper Norwood Recreation Ground, Upper Norwood, and flows through West Norwood (which is the north and northwest of Norwood). Where Norwood High Street merges at the fountain with the A215 to form Norwood Road it is joined by a small tributary from Knights Hill Ward where it flows NNE. A second branch rises south of Gypsy Hill into West Dulwich via Croxted Road, after flowing from near The Westow House[n 1], Westow Hill down the middle section of Jasper Road following the railway tunnel which ends then becomes the sewer under the road Gipsy Hill. After the Paxton Pub opposite the end of Gipsy Hill it captures water from Hamilton Road, forms the back garden line of Croxted road and joins the other branch at the South Circular where it now forms the sewers of Croxted Road, Dulwich Road, Dalberg Road, Effra Road, Electric Lane, Brixton Road, Harleyford street/road separated by the Kennington Oval.[3] The name cannot be traced back much earlier than 1840,[5][6]

Additional tributaries: One channel forms in Belair Park, going under Burbage Road and Half Moon Lane, Dulwich and North Dulwich to join at Dulwich Road. A further stream ran from Tulse Hill instead west past Knights Hill down Leigham Vale to join at Dulwich Road.[2]

Local folklore tells of a coffin found floating down the Thames in Victorian times which was traced back to West Norwood Cemetery[n 2]. Mysteriously, the grave the coffin came from was apparently undisturbed. Further investigation revealed that the ground beneath the grave had subsided and the entire coffin fell into the underground Effra river and floated downstream.[3]

Mainly underground, what remains of the river Effra is somewhat less than what used to contribute to its source, being replaced by an extensive surface water separate drainage system — due to its convenient contours however to the early development of its adjoining neighbourhoods it is a sewer in same way as the Walbrook which rises and flows in the City of London and certain other former London rivers and streams.[3]

Although little more than a stream in the south, until 1935 the encased watercourse flooded during heavy rains every decade or so; an inscription on a white stone tablet high up the side of a building in Elder Road, West Norwood reads: "FLOOD LEVEL 17th July 1890".[2]

After a three-hour-long storm on Sunday 14 June 1914 the sewer overflowed again and flooded houses along its path from Elder Road to Chestnut Road, and locals were forced to evacuate their homes for several days. Further floods in the 1920s prompted works to enlarge the sewer. This was sufficient until a small part of the local area was flooded again during a powerful downpour on 20 July 2007.[2]

In 1992 a project by the London arts group Platform sparked a local campaign to dig up the river. The 'Unearthing the Effra' project was based around a mock 'Effra Redevelopment Agency', which included a public office. The project gained publicity in local newspapers and radio stations.[2]